Charles James O'Donnell, born in Donegal and educated in Galway, provided in his will (1935) for a bequest to each of the Universities of Oxford, Wales, Edinburgh, National University of Ireland and Trinity College, to establish an annual lecture in each of the institutions - the lecture in the National University of Ireland to be on the history of Ireland since the time of Cromwell, with particular reference to the histories, since 1641, of old Irish families. The lecture series was established in 1957 and continued until 1986. Due to a lack of funds there was a gap of some years, but the NUI Senate was pleased to be able to revive the series, to be presented annually in each of the NUI Constituent Universities in rotation, as and from 1999. This, the 31st lecture in the series, was delivered by Daibhi O Croinin in the O Tnuthail Lecture Theatre, National University of Ireland, Galway. Daibhi O Croinin is Professor of History at NUI, Galway. Since 1982 he has been co-editor (with Prof. Donnchadh O Corrain, UCC) of Peritia: journal of the Medieval Academy of Ireland, and is a member of the Royal Irish Academy. He is the author of Early Irish History and Chronology (Dublin, 2003) and Whitley Stokes (1830-1909): The lost Celtic notebooks rediscovered (Dublin, 2011).